In order to help save more money and funnel more of those savings to debts, I'm looking for more ways to save money.

I've heard that puting plastic window insulation over single-pane windows typically found in older houses can reduce utility bills by up to 50%.

But I'm wondering, it's February, and I'm in Portland, Oregon, USA. Summers can get as hot as 100 degrees fahrenheit in the extremes. Living in a temperate climate, is there an advantage to keeping the plastic up year round, or will I just need to remove it in the Spring/Summer?

To further clarify and address the "airing out the house" issue, let's say that I only open two windows upstairs and two windows downstairs. There are 14 windows total in the house, plus 1 door upstairs and two doors downstairs, one in the front and one in the back.

My motivation for asking is to determine if the inputs I put in now in the form of putting up all that plastic in February will pay any dividends, or if it's best I wait until October.

This might make sense, if you artificially control the temperature inside your house year round. However, in the spring and fall, I tend to like to open the windows "to blow the stink out".
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Tester101♦Feb 11 '13 at 14:08

@Tester101 - Great point. Although I'm not sure this is an issue due to the number of doors in the house. I edited my post to further clarify.
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jmort253Feb 13 '13 at 2:51

The benefit of having double pane, or well insulated windows, is greater when it's cold, then when it's hot. My Florida house, built in 2004, has single pane windows, as is the standard for most builders here.
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EdwinApr 15 '13 at 22:55

8 Answers
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Single pane windows are horribly inefficient. Having the plastic up will pay dividends for the remainder of the winter and if you use AC in the summer it will help there as well. As for airing out the house when its a nice day, you could just remove the film from a couple windows to get the airflow going.

Hi @DSawyer - Thank you for your answer! Do you by chance have references for this? Or perhaps you've experienced this yourself and could be specific as to how much this saved you on your energy bills percentage-wise? Thanks again! :)
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jmort253Feb 17 '13 at 19:48

If the plastic reduces air exchange between your home and the outside world in the wintertime, it will do the same thing for you in the summertime. You will get some benefit from the plastic in the summertime. I can't tell you how large of a benefit. But, based on my own experience, the tape that holds the plastic in place tends to grow loose after a season or two, so the quality of seal will deteriorate and you may find yourself having to put new plastic up anyway to maintain the seal.

Also, in my home (1921 with single pane windows) the impact of the plastic could not really be measured in terms of utility bills. It was nowhere near 50%. You will probably find that it makes the room much more comfortable, though.

The plastic will help you in the winter, but it's pretty much useless in the summer. Sunlight on the roof and coming through windows is a far bigger issue than heat exchange in the summer (45-55% of the cooling load in air-conditioned homes) and window plastic won't help with that. It will help stop air leaks, but you can do that with cheap caulk and weatherstripping without sacrificing the ability to open the windows. In the summer, you'll be better off putting up cheap awnings to shade south-facing windows. Save the plastic for next winter.

As for the plastic's effect on utility bills, I don't see how it could cut your total costs by 50% unless every part of the house but the windows is absolutely perfect. It might cut your window-related costs by 50% in winter, but windows are far from the only source of energy waste in any home. The walls, floors, and ceiling probably account for more air leakage than the windows, although those leaks are usually not as obvious.

I realize hoping for 50% gains isn't standard and that results will vary, but anything to get those bills lowered would be helpful. What you're saying though, if I understand, is that leaving the plastic on in the summer won't help much, but it won't hurt either.
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jmort253Apr 16 '13 at 0:49

If you aren't using the windows for ventilation, it shouldn't hurt to leave it up in the summer. For reference, 50% savings might be realistic if your landlord paid for a whole-house retrofit with air sealing, insulation, efficient HVAC system, etc., depending on the current condition of the house.
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Evan JohnsonApr 16 '13 at 16:25

Any possible thing you put in front of your window is going to keep the outdoor temperature from coming in. Aluminum foil, plastic, trash, bookcase, whatever. Some will do a better job than others. Some will do so while making your window usable like weatherproofing strips. Others make it almost completely non-functional - like plastic. What is the R value in your plastic - well that depends on how thick the plastic is, what its made of, and the tape job around it. Will your energy bills be less - Yes. Whatever you put up will make your energy bill less. Maybe a few pennies a year maybe a few hundred dollars. Maybe the body heat produced thinking about this and putting up the plastic saved more than the plastic itself. I seriously doubt 50% unless you had some very drafty windows.

Starting with the assumption of 50% savings, the implication to me is that the windows are very leaky - letting a lot of air pass. That's because even a new window with insulated glass would not be expected to make that big of an impact based solely on the insulation value of the glass assembly or, in this case, the insulating plastic does not add that much to the insulating properties window.
Sealing the places where air leaks through the window assembly would have a bigger effect. (By the way, you'll notice on the site to which you linked, that part of the promotion is that this product can help stop air leaks). The plastic film could be installed over the entire window all the way to the surrounding trim or even the wall and that would prevent air from passing in and out of the house. But there is a better way.
Depending on your specific window, you should be able to find various types of weatherstripping materials that allow the windows to operate normally and can stay in place for years. That would be well worth the effort. If you like, tell us more about your particular windows.

Hi Geos, while I appreciate the explanation, this isn't really answering my question. I rent, so I'm not looking at spending too much money or time on a property that isn't my own personal investment. My question is more about whether or not putting up plastic in February/March would be a waste or will it carry into next winter, and survive/be effective in the summer.
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jmort253Feb 15 '13 at 15:07

I've found that the plastic for old windows in the winter saves about 30% percent on heating costs. The plastic in the summer may help somewhat but weather stripping boosts the plastic's effect in the winter and allows you to open windows in the summer.

I would most recommend weatherstripping for the summer because natural cooling can save a bundle! I use thermal window coverings (curtains) to keep heat down in the day and open windows after sundown and close them at sunrise. Our house has no AC (and we've bought no window AC's) yet it stays about 70-76 degrees all summer (which is crazy now that it's July).

I genuinely feel that placing plastic, of which any kind that involves the double sided tape reduces your air leakage via any window. Our town home is only 8 years old but the drafts are amazing since we are high up on a hill. Sitting at the bottom of the staircase it is quite evident with the air flow. I very tediously cut the plastic a bit bigger than the area I'm trying to cover to alleviate any spaces. Then blow dry it to secure it more firmly. I believe this method works and we save 20% on our hearing costs thru the winter months. Make certain your windows are shut right and locked and purchasing a layered curtain deals the deal. I use the plastic under the blinds also so I can still manage the light during the daytime with use of the sunlight. Good luck in your plastic adventure. Any box of plastic is useful!

The problem with retaining the plastic in summer is that it keeps you from opening the windows and taking advantage of the natural cooling often available at night or on cooler days.

If you're never going to open those windows (I almost never open the ones onto my porch), there's no harm done in leaving the plastic up; it may or may not survive until/through next heating season depending on many factors from humidity to how clean the surfaces were before you installed the double-stick tape.

I do use the window film on my old windows. I'd somewhat prefer interior storm windows, for the sake of elegance, of being able to open and re-close without having to go through the whole heat-shrinking routine again, and because they'd work MUCH better on the bay window. But I haven't been willing to make that investment yet.